I've packaged it up for Installer now [UPDATE, NEW INSTRUCTIONS], if you have an OTB 1.1.2/1.1.3, you will need to:downgrade to 1.1.1,
jailbreak,
install this package,
OkToPrep and updgrade/jailbreak 1.1.2 (just hold down Option (shift in Windows) while pressing upgrade, and point iTunes to the 1.1.2 firmware file)
and then install the DevTeam upgrade to get back to 1.1.3.

You'll wind up with an unlocked 1.1.3 with the 4.6 BL. (thanks, BigBoss, for suggestion).

I will be looking into a native app to run this, so you can run it straight from 1.1.3. I'll let ya know.

DO NOT RUN THIS ON A 3.9 BL iPHONE - it will be bad.

DO NOT RUN THIS FROM 1.1.2 or 1.1.3. There are a few sources that are offering this package to run straight from 1.1.3 - THIS IS NOT GOOD. You can brick your iPhone. When in 1.1.2 or 1.1.3, this NEEDS to be run from Airplane Mode, which you CANNOT DO from Installer. This is why we currently only have this on 1.1.1. I will say again, IF YOU INSTALL A PACKAGE LIKE THIS WHILE IN 1.1.2 or 1.1.3, YOU CAN BRICK YOUR iPHONE.